Circulating ovarian steroid hormones, estrogen (E) and progesterone (P), have a profound modulatory in brain cells that ensure both the release of pituitary gonadotropins which trigger ovulation and the synchronous expression of behavioral receptivity. We have recently reported that both epidermal growth factor (EGF) and insulin growth factor-1 (IGF-1) exert influences on hypothalamic steroid receptors in the absence of E and/or P. At present, the molecular and cellular mechanisms and interneuronal interactions underlying ligand-independent regulation of steroid receptor-dependent function in the central nervous system (CNS) are undefined. Receptors for both EGF and IGF-1 are expressed in hypothalamic regions linked to reproduction. The goal of this project is to characterize critical signal transduction and phosphorylated molecules (the tyrosine src kinase, cAMP, CREB, STAT3, SRC-1, ERalpha, ERbeta, and OSCP) in the brain for an effect of E and EGF on downstream gene targets. By using a blend of present molecular technology (in vivo use of antisense oligonucleotides, mutant mice model, characterization of individual cell mRNA population and differential display) with powerful neuroanatomical tools (immunohistochemistry, in situ hybridization, patch clamp dialysis), the relationship between E and EGF will be examined in order to devise new, more effective treatment strategies for reproductive disorders associated with E. The proposed in vivo studies of ligand-independent activation of ER are at an early stage, but are absolutely required for understanding physiological responses at the molecular and cellular level within the CNS which mediate neuroendocrine control of ovulation and reproductive function.